Atomic Force Measurements of Hydrophobic Interactions

This semester project comes within the scope of studies at the nanometre scale. The experimental techniques used in this work are related to atomic force microscopy, which gives a direct access to the topography and forces of the studied systems. The goal of this project is to study dependence of local humidity and ambient on hydrophobic interactions by a series of systematic experiments on several samples. The experimental part of the semester project consists in the execution of force measurements with an AFM to pick the adhesive force and work of adhesion up. With those measures I calculate the contact angle, which characterize the hydrophobicity of a sample. To have more data to compare, I realize this experiment with four different samples (one hydrophilic and three hydrophobic) with five different ambient conditions. The data picks up permit us to compare value of the contact angle of a sample. They also permit to compare the interaction tip-­‐sample with the other material. The main results observed are coherent with those we can find in literature and the contact angle shows the character hydrophobic or hydrophilic of each sample. The increase of the force of adhesion with the increase of humidity is also a result shown in this project.